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New Member

find IP address by MAC address ????

hi ~

i would like to find an IP address that already connect to CISCO switch. as ...

- when i do 'sh int' it show the MAC address of switch port. (last digit is running number by port)

- when i do 'sh mac' it show the only MAC whitch start with 0080

- when i do 'sh ip arp' on core router using this 0080 address it show many IP addresses connect to same virtual interface.

- when i do 'sh cam' on core switch using this 0080 address it show the port that is uplink to the switch.

(- " ---#) confuse already ... could anyone tell me how to find IP address if you know MAC address ? did i do something wrongly ? i've tried 'arp' command on my normal command prompt also but couldn't find ... HELP PLEASE ~ !!

thanks in advance,


Re: find IP address by MAC address ????

I would like to know what are your switches models and the software they are running.

Anyway, in my network, when I need to find an IP address by MAC address what I usually do is to connect to our core router and run:

show arp | include A.B.C.D

when A.B.C.D is the MAC address I'm looking for. You can even run this command although you only know a few bits of the MAC address. For example:

show arp | include 0080


New Member

Re: find IP address by MAC address ????

hi (again) ~

thanks for your reply ... now i know already that the list of IP address that i got after do 'sh arp' at core router has only 1 IP that can ping so the thing that connects to the switch port is that one. (^ - ^bb)


anyway just in case you want to know the story ...

the connection will be like this ...

4006 (v. 6.2(2))---> 2912 ---> [??? IP]

anyway i've tried all command for every switch & router will summarize as the following ...

- 4006 switch : cannot use " | "

4006 sh cam ?

agingtime Show cam aging time

count Showing cam total entries

dynamic Show dynamic cam entries

mlsrp Show cam Multilayer Switching Router info

permanent Show permanent cam entries

static Show static cam entries

system Show system cam entries

MAC address

so i used ...

4006 sh cam

and it reply with physical port that connect to 2912 switch

4006 sh arp ?

noalias Display IP address instead of alias hostname

IP address or hostname

so i used it, and it replied with many IP connect at vitual interface

- 4006 router also cannot use " | "

4006# sh arp | ?

% Unrecognized command

4006# sh arp ?

- 2912 can use " | " as you said but it never reply with the MAC or IP i want ... it reply with only IP & MAC on VLAN 1

2912>sh arp ?

| Output modifiers



Re: find IP address by MAC address ????

#sh mac-address-table address ?

H.H.H 48 bit mac address